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Another study highlights the insanity of selling junk food in school vending machines

These vending machines at Los Angeles High School -- and others like them… (Barbara Davidson/Los Angeles…)

For many students, “back to school” means back to a vending machine diet. As you might guess, this isn’t necessarily a good thing for student health.

Vending machines are found in 16% of U.S. elementary schools, 52% of middle schools and 88% of high schools. About 22% of students in grades 1 through 12 buy food in vending machines each day – and those purchases added an average of 253 calories to their diets, according to a new study in the September issue of the Journal of School Health.

Just to be clear, those were not 253 calories' worth of tofu, yogurt or carrot sticks. The most popular vending machine items included soft drinks, candy, chips, crackers, cookies, cakes and ice cream. On the plus side, kids also bought low-fat milk, fruit juice and even fruit, the study found.

But the net effect on kids’ diets was not good. Those who bought from vending machines ate an average of 156 grams of sugar per day, compared with 146 grams for those who abstained. They also consumed less dietary fiber, iron and B vitamins like thiamine, riboflavin, niacin and folate.

One silver lining: Vending machine customers ate 4% less sodium than other students – an average of 3,287 milligrams per day compared with 3,436 mg for those who didn’t buy from vending machines. That’s probably because the extra snacks made kids too full to eat as much at mealtime, when dishes are especially salty. In any event, kids should eat no more than 1,200 to 1,500 mg of sodium each day, according to the Mayo Clinic. (Even for adults, the government recommends a daily limit of 2,300 mg.)

Overall, vending machines in school appear to be taking a toll on public health. The researchers – from the University of Michigan, Michigan State University and Food & Nutrition Database Research Inc. of Okemos, Mich. – calculated that all that snacking adds up to about 14 extra pounds per child per school year.

“For some students this might be a serious contributor to weight issues,” they wrote. Other public health problems include Type 2 diabetes and cavities.